Team:KU Leuven/Project

Our goal is to create a sustainable system to reduce the damage that aphids cause to our agricultural industry. The current solution usually requires huge amounts of insecticides, damaging ecosystems in several ways. First, the indiscriminate weakening of insects means that beneficial insects (pollinators, ...) are also affected. Second, insecticides affect vertebrates, including humans, damaging our health (Bjørling-Poulsen et al., 2008). Third, insecticide residues (catabolites) accumulate in each food-chain. The highest organism, be it humans or for example predatory birds, will end up with potentially high levels of residues and their negative effects.
We aim to offer an effective and sustainable alternative for insecticides. Our modified E. coli (‘BanAphids’, meaning ‘to ban aphids’ as well as with ‘benefits’) would produce the aphid’s own alarm pheromone, E-β-farnesene, (EBF) to repel them off the plant. On top of that we want to attract aphid predators such as the ladybug via the production of methyl salicylate (MeS), a phytohormone, by our BanAphids. This way we ensure aphids are thoroughly removed from the plant.
We have established some of the potential hurdles when introducing this system in agriculture. First, the plant’s metabolism should not be overburdened. Second, aphids might habituate to constitutive expression of EBF (De Vos et al., 2010, Kunert et al., 2010). Finally, we do not want to attract the aphid’s natural predators when they are not needed.
We devised two different methods to implement our system. One method would be to spray our BanAphids onto the plants. To minimise the burden on the plant’s metabolism and attract predators only when needed, our BanAphids will only produce MeS when aphids are present. Another way to avoid habituation of the aphids is an oscillating production of EBF, which requires a colony-wide synchronized oscillating system.
Our second method starts from the principle that the BanAphids may not come in direct contact (for instance, because of safety issues) with the plants and the aphids these would carry. To ensure this, we developed an oscillating system such that the BanAphids could alternate between MeS and EBF production without the ``aphid present` signal. We will place our BanAphids in a container, isolated from the environment but producing MeS and EBF in an oscillating pattern, to prevent habituation. We turned to the sticker model of the Groningen 2012 iGEM team to use as a container. The sticker is composed of a plastic film, whose pores are too small for the BanAphids to pass but large enough so the volatile pheromones it produces still pass. The Groningen 2012 iGEM team has already investigated the biosafety of this sticker.

Sticker model